1. Field of the Invention
The invention relates to a light-filtering module, and more particularly to a light-filtering module applied in a projecting system.
2. Description of the Related Art
When projectors are in use, output effects are required for particular situations, such as home theatre projectors with real color and brief report projectors with high brightness.
FIG. 1 is a spectrum energy distribution diagram of a UHP light source. For visible light within the range between 380-780 nm wavelength, two high energy peaks of 550 nm wavelength of green light and 570 nm wavelength of yellow light, are characterized with the following features when used in projectors for different applications.
For home-theatre projectors to approach real color, a precise color performance and green light precisely purified by filters are required. Thus, the filters are configured to block 570 nm wavelength of yellow light, i.e., allowing penetration of 550 nm wavelength of green light. Because 570 nm wavelength of yellow light is being neglected, brightness of home-theatre projectors is therefore lowered.
For brief-report projectors to be used by several users at the same time, a high brightness output is required. Thus, the filters are configured to block 550 nm wavelength of green light, i.e., allowing penetration of 570 nm wavelength of yellow light. Because 570 nm wavelength of yellow light is allowed to penetrate, brightness of brief-report projectors can be increased. However, due to 550 nm wavelength of green light contained with the yellow light, color performance of brief-report projectors may be hindered, as the green light contained with the yellow light is incorporated with lights containing real colors.
Based on the described features of the home-theatre and brief-report projectors, there is no projector capable of providing precise color performance and high brightness output.